I would also suggest looking a bit more into UX and design. At least for front-end work. It’s a really tough subject and I’m by no means a great designer myself. It’s something i really want to improve at, but there are only so many hours in a day.
One point i would make about your CSS. You have some extremely long selectors with high specificity, targeting elements. IMO it can be improved by giving classes to your elements.
Div#section3 div > div > ul.cards li > a > img
This is not a great selector and i don’t think you will find many professional developers writing CSS like this. I would look into oocss, smacss and bem. Even if you don’t like those methodologies, you should know and learn about them.